'\" et
.TH PTHREAD_MUTEXATTR_GETPRIOCEILING "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
pthread_mutexattr_getprioceiling,
pthread_mutexattr_setprioceiling
\(em get and set the prioceiling attribute of the mutex attributes object
(\fBREALTIME THREADS\fP)
.SH SYNOPSIS
.LP
.nf
#include <pthread.h>
.P
int pthread_mutexattr_getprioceiling(const pthread_mutexattr_t
    *restrict \fIattr\fP, int *restrict \fIprioceiling\fP);
int pthread_mutexattr_setprioceiling(pthread_mutexattr_t *\fIattr\fP,
    int \fIprioceiling\fP);
.fi
.SH DESCRIPTION
The
\fIpthread_mutexattr_getprioceiling\fR()
and
\fIpthread_mutexattr_setprioceiling\fR()
functions, respectively, shall get and set the priority ceiling
attribute of a mutex attributes object pointed to by
.IR attr
which was previously created by the function
\fIpthread_mutexattr_init\fR().
.P
The
.IR prioceiling
attribute contains the priority ceiling of initialized mutexes. The
values of
.IR prioceiling
are within the maximum range of priorities defined by SCHED_FIFO.
.P
The
.IR prioceiling
attribute defines the priority ceiling of initialized mutexes, which is
the minimum priority level at which the critical section guarded by the
mutex is executed. In order to avoid priority inversion, the priority
ceiling of the mutex shall be set to a priority higher than or equal to
the highest priority of all the threads that may lock that mutex. The
values of
.IR prioceiling
are within the maximum range of priorities defined under the SCHED_FIFO
scheduling policy.
.P
The behavior is undefined if the value specified by the
.IR attr
argument to
\fIpthread_mutexattr_getprioceiling\fR()
or
\fIpthread_mutexattr_setprioceiling\fR()
does not refer to an initialized mutex attributes object.
.SH "RETURN VALUE"
Upon successful completion, the
\fIpthread_mutexattr_getprioceiling\fR()
and
\fIpthread_mutexattr_setprioceiling\fR()
functions shall return zero; otherwise, an error number shall be
returned to indicate the error.
.SH ERRORS
These functions may fail if:
.TP
.BR EINVAL
The value specified by
.IR prioceiling
is invalid.
.TP
.BR EPERM
The caller does not have the privilege to perform the operation.
.P
These functions shall not return an error code of
.BR [EINTR] .
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
None.
.SH RATIONALE
If an implementation detects that the value specified by the
.IR attr
argument to
\fIpthread_mutexattr_getprioceiling\fR()
or
\fIpthread_mutexattr_setprioceiling\fR()
does not refer to an initialized mutex attributes object, it is
recommended that the function should fail and report an
.BR [EINVAL] 
error.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIpthread_cond_destroy\fR\^(\|)",
.IR "\fIpthread_create\fR\^(\|)",
.IR "\fIpthread_mutex_destroy\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<pthread.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
